NATURE OF THE FOOD OF ANIMALS. 145 



144. The first division of aliments is naturally into those 

 which are derived from the Animal and Vegetable kingdoms 

 respectively. Wherever plants exist, we find animals adapted 

 to make use of the nutritious products they furnish, and to 

 restrain their luxuriance within due limits. Thus among 

 Mammals, the Dugong (an animal having the general form 

 and structure of the whale, but adapted to a vegetable diet) 

 browses upon the sea-weeds that grow beneath the surface 

 of the tropical ocean ; the Hippopotamus roots up with his 

 tusks the plants growing in the beds of the African rivers, 

 and fills his huge paunch, not only with these, but with the 

 decaying vegetable matter which he finds in the same situa- 

 tion ; the Antelopes, Deer, Oxen, and other Ruminants, crop 

 the herbage of the plains and meadows ; the Giraffe is enabled 

 by his enormous height to feed upon the tender shoots which 

 are above the reach of ordinary quadrupeds ; the Sloths, living 

 entirely in trees, and hanging from their branches, strip them 

 completely of their leaves ; the Squirrels extract the kernels 

 of the hard nuts and seeds ; the Monkeys devour the soft 

 pulpy fruits ; the Boar grubs up the roots and seeds buried 

 under the soil ; the Reindeer subsists during a large part of 

 the year upon a lichen that grows beneath the snow; and 

 the Chamois finds a sufficient supply in the scanty vegetation 

 of Alpine heights. Not less is this the case among 'Birds ; 

 but in the classes of Reptiles and Fishes, the number of 

 vegetable-feeders, and consequently the variety of their food, 

 is much less. 



145. Among Insects, a very large proportion derive their 

 food entirely from Plants, and many from particular tribes of 

 plants only; so that, if from any cause these should fail, the 

 race may for a time disappear. There is probably not a 

 species of plant which does not furnish nutriment for one or 

 more tribes of insects, either in their larva state or their per- 

 fect condition ; and in this manner it is prevented from mul- 

 tiplying to the exclusion of others. Thus, on the Oak no less 

 than two hundred kinds of caterpillars have been estimated 

 to feed ; and the Nettle, which scarcely any beast will touch, 

 supports fifty different species of insects, but for which 

 check it would speedily annihilate all the plants in its neigh- 

 bourhood. The habits and economy of the different races 

 existing on the same plant, are as various as their structure. 



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